The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Substrate processing systems such as semiconductor processing systems may be used to deposit film layers, metal layers or other types of layers onto a substrate such as a semiconductor wafer. The substrate processing system may include one or more processing stations. While semiconductor wafers used in microelectronic production currently have diameters in the range of about 150 mm to 300 mm, next-generation tools are expected to handle 450 mm wafers. Similarly designed substrate processing systems are also used to process large rectangular glass plates for applications such as photovoltaics, flat panel displays, and electrochromic windows.
A substrate handling robot associated with a vacuum transfer chamber may be used to move the substrates from a load lock to one of the processing stations of the processing chamber and/or between the stations of the processing chamber. The vacuum transfer chamber allows the transfer to be performed in a vacuum. Gases are typically introduced into the vacuum transfer chamber through a gas delivery tube or a gas diffuser connected to the vacuum transfer chamber. A location of the gas delivery tube or the gas diffuser is stationary relative to the vacuum transfer chamber.
During transfers, it is desirable to avoid degradation of the film layers of the substrate. For example only, one processing station may deposit a dielectric layer onto a wafer. Degradation of the dielectric layer may occur when transferring the wafer through the vacuum transfer chamber to another one of the processing stations. For example only, another processing station may deposit a metal layer, such as copper, onto the wafer. Oxidation of the metal layer may occur when transferring the wafer through the vacuum transfer chamber. Unwanted contamination such as hydrocarbons in the residual gases of the vacuum transfer chamber as well as particles may also deposit onto the wafer surface during transport.
Current technology to inhibit oxide formation or dielectric degradation on the substrate typically involves using high gas flows to dilute oxygen or water vapor content. The pressure setting in the vacuum transfer chamber is usually a constant value that is based on the application performed in the wafer process modules (e.g. deposition or etch). The high gas flow generally requires large capacity vacuum pumps to hold chamber pressure at a constant pressure value. Large capacity pumps are typically more expensive and have a relatively large footprint, which tends to increase cost per unit area in a fabrication facility.